NVMe: Add a pci_driver shutdown method

We need to shut down the device cleanly when the system is being shut down.
This was in an earlier patch but was inadvertently lost during a rewrite.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 89021d7..eaace76 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -2554,6 +2554,12 @@
 	return result;
 }
 
+static void nvme_shutdown(struct pci_dev *pdev)
+{
+	struct nvme_dev *dev = pci_get_drvdata(pdev);
+	nvme_dev_shutdown(dev);
+}
+
 static void nvme_remove(struct pci_dev *pdev)
 {
 	struct nvme_dev *dev = pci_get_drvdata(pdev);
@@ -2625,6 +2631,7 @@
 	.id_table	= nvme_id_table,
 	.probe		= nvme_probe,
 	.remove		= nvme_remove,
+	.shutdown	= nvme_shutdown,
 	.driver		= {
 		.pm	= &nvme_dev_pm_ops,
 	},